Litigation (Details) $ in Millions					1 Months Ended		9 Months Ended	36 Months Ended
	Jul. 22, 2016 USD ($)	Jul. 02, 2013 USD ($)	Aug. 03, 2012 USD ($)	Feb. 14, 2011 USD ($)	Sep. 30, 2010 USD ($)	Aug. 31, 2010	Sep. 30, 2016 LegalMatter	Dec. 31, 1993 breach	Nov. 13, 2013 USD ($)	Nov. 06, 2012	Jan. 03, 2012	Dec. 31, 2008 USD ($)	Dec. 31, 1998 USD ($)
Loss Contingencies [Line Items]
Number of contract breaches | breach								7
MTBE [Member] | Pending Litigation [Member]
Loss Contingencies [Line Items]
Pending lawsuits and claims (in number of claims) | LegalMatter							6
Ecuador [Member]
Loss Contingencies [Line Items]
Litigation settlement, amount	$ 96
Litigation Settlement, Amount, Including Interest	$ 113
Ecuador [Member] | Pending Litigation [Member]
Loss Contingencies [Line Items]
Remediation program													$ 40
Conducted remediation program (in years)							3 years
Financial compensation for purported damages on mining engineer's report												$ 18,900
Assessment for purported unjust enrichment on mining engineer's report												$ 8,400
Court order requiring the parties to provide their positions on damages within (in days)						45 days
Amount assessed in damages				$ 8,600					$ 9,500
Amount assessed for plaintiffs representatives				900
Additional amount assessed in punitive damages				$ 8,600
Public apology date within judgment/clarification ruling (in days)				15 days
Proposed additional payment for plaintiff attorney fees as percentage of judgment											0.10%
Litigation settlement, amount			$ 19,100
Percentage of payments withheld by third parties due to freeze order										40.00%
Percentage of funds wIthheld by banks due to freeze order										40.00%
Ecuador [Member] | Pending Litigation [Member] | Minimum [Member]
Loss Contingencies [Line Items]
Approximate damages on plaintiffs' submission					$ 16,000
Approximate unjust enrichment on plaintiffs' submission					5,000
Ecuador [Member] | Pending Litigation [Member] | Maximum [Member]
Loss Contingencies [Line Items]
Approximate damages on plaintiffs' submission					76,000
Approximate unjust enrichment on plaintiffs' submission					$ 38,000
Embargo Order [Member] | Ecuador [Member]
Loss Contingencies [Line Items]
Litigation settlement, amount		$ 96
Declatory Relief Claim [Member] | Ecuador [Member] | Pending Litigation [Member]
Loss Contingencies [Line Items]
Pending lawsuits and claims (in number of claims) | LegalMatter							1
Discovery Stay On Claims [Member] | Ecuador [Member] | Pending Litigation [Member]
Loss Contingencies [Line Items]
Pending lawsuits and claims (in number of claims) | LegalMatter							8